Folding panel construction

ABSTRACT

A self-erecting foldable display structure has a continuous display panel supported by a collapsible frame secured to its reverse side. The support frame includes an elongated back panel and a pair of side panels integrally hinged to the respective longitudinal edges of the back panel. Transverse fold lines are formed in both the support frame and the display panel dividing the structure into a plurality of sections. A combination of flaps and elastic bands in the support frame tend to maintain the frame with a U-shaped cross-section, thereby preventing folding of the structure. Manual flattening of the side panels against the pull of the elastic bands permits the structure to be folded along the transverse fold lines into a substantially flat, compact package. When the folded structure is held at its upper end and allowed to unfold freely, the support frame automatically reassumes its U-shaped configuration and supports the display panel in a substantially vertical position.

0 United States Patent 1 1 1 3,727,874 Wuensch 1 Apr. 17, 1973 FOLDINGPANEL CONSTRUCTION Primary ExaminerR0y D. Frazier [75] Inventor: John H.Wuensch, Leonia, N..l Assistant Examm,er R0dney Bonck Attorney-Granv1lleM. Brumbaugh et a1. [73] Assignee: Electronic Assistance Corporation,

Fair Lawn, NJ. [57] ABSTRACT [22] Filed: Sept. 17, 1971 A selferectingfoldable display structure has a continuous display panel supported by acollapsible frame [21 1 App]. 181368 secured to its reverse side. Thesupport frame includes an elongated back panel and a pair of side panelsin [52] US. Cl. ..248/459, 248/174, 248/460 tegrally hinged to therespective longitudinal edges of [51] Int. Cl. ..A47f 5/11 the backpanel. Transverse fold lines are formed in [58] Field of Search..248/459, 174, 450; both the support frame and the display paneldividing 211/72, 73 the structure into a plurality of sections. Acombination of flaps and elastic bands in the support frame [56]References Cited tend to maintain the frame with a U-shapedcross-section, thereby preventing folding of the structure T D STATESPATENTS Manual flattening of the side panels against the pull of350873'4 4/1970 Thomasum v 248/459 the elastic bands permits thestructure to be folded 7435,1558 1/1922 p h along the transverse foldlines into a substantially flat, 2 72 933 2 17 compact package. When thefolded structure is held at 2,803,076 8/1957 Viglietta... 248/459 itsupper end and allowed to unfold freely, the support 2,940,710 6/1960Adams 248/174 frame automatically reassumes its U-shaped configura-582,333 5/1897 Wright v .2] H73 ti n and suppgrts the display panel ina, substantially 2,611,572 9 1952 Rocca ...248/174 vertical position1,962,089 6/1934 Davidson ..248/459 13 Claims, 4 Drawing Figures 1 -2751b 26 l/c PATENTEDAPR 1 H975 sum 1 or 2 FIG? FOLDING PANEL CONSTRUCTIONThis invention relates to foldable structures for advertising displays,article support, etc., and more particularly to such a structure formedof self-supporting sheet material which can be easily folded to form acompact package and yet is effectively self-erecting to provide asturdy, self-supporting construction especially suited for the displayof advertising messages.

In so called point of sale" advertising, wherein an advertising messageis to be brought to the consumer in the shop or market where theadvertised product is sold, it is a regular practice of either themerchant or the supplier of the product to provide vivid, eyecatchingdisplays closely adjacent to the supply of the product on the merchantsshelves to attract the attention of the consumer. Generally, thesedisplays are supplied to the merchant by the salesman of the product andare of the type that may be quickly set up and taken down by thesalesman without special equipment or assistance.

One such class of advertising displays comprise advertising messagescarried by a panel formed of paperboard, cardboard or similarself-supporting material which is held in a generally upright positionby means such as an easel or a self-contained foldable support frame.The latter is particularly advantageous since it can be formed of thesame material as the display panel, is generally lighter in weight andless bulky than separate supporting structures and is less expensive.One such type of support frame consists of a sheet of paperboard whichcan be folded to form a channel of U-shaped cross section with the sidepanels of the channel being retained in that position by spacers and Velastic bands. The frame and the spacers may be flattened out and theframe folded to reduce itsbulk for transporting. The display mediumcarried by the sup.-

port frame consists of a plurality of separate panels secured to thereverse side of the support frame. Thus, when the side panels of thesupport frame are flattened, the frame may be folded in the longitudinaldirection between the display panels to provide a package easily carriedby a salesman. This form of construction is e xemplified in U.S. Pat.No. 3,508,734, granted Apr. 28, 1970, to l-l.C. Thomas.

While such constructions provide advantages in portability and abilityto be erected and collapsed, they still present certain drawbacks whichdetract from their utility and ability to present an advertising messageof I sufficient eye impact. These prior art structure are unduly complexin design and manufacture and have structural weaknesses which limit thenumber of times they may be collapsed and erected without damage.Moreover, these constructions require that the advertising display bedivided into completely separate panels with spaces therebetween,thereby limiting the format of the message carried by the panel anddetracting from its appearance and advertising impact.

ln accordance with the present invention, these drawbacks have-beeneliminated to provide a structure in which a continuous advertisingpanel is supported in an upright position by a simple, sturdy supportframe. Both the panel and support frame may be readily collapsed intoacompact package and the structure is completely self-erecting in areliable manner simply by allowing gravity to unfold it.

Briefly, the support frame structure comprises an elongated sheet ofself-supporting paperboard or the like provided with longitudinal foldspermitting it to be formed into a U-shaped channel, and one or moretransverse score lines to enable it to be folded into a compact package.Pairs of flaps are punched out of the paperboard material so as to behinged along scores in the side panels of the U-shaped channel. Theseflaps are adapted to engage detents in the back panel of the supportframe formed by the same cut-outs which provide the flaps. One or moreelastic bands interconnect the pair of side panels so as to urge themtowards one another and at the same time direct the flaps intoengagement with their respective detents. The interaction of the flaps,detents and elastic bands form the support frame into a rigid, loadsupport U-shaped channel, which at the same time, may be readilyflattened and folded.

The advertising or display panel may be a single continuous sheet ofpaperboard or the like (or several sheets fastened together to form anuninterrupted surface) and is secured, such as by gluing, to the backpanel of the support frame. The display panel is provided with foldlines corresponding to the transverse fold lines in the support frame sothat the composite support frame-display panel structure may be foldedalong its longitudinal direction to produce a compact package. To permitfolding of the display panel while accommodating the extra thicknessprovided by the support frame, each of the fold lines in the displaypanel is cut through for that portion of its length which is coextensivewith the support frame when flattened for folding. The remainder of thefold lines are merely crimped or scored. This permits the display panelto expand or open up slightly to accommodate the support frame materialwhen folded and yet present a continuous surface when erected. Thus, theadvertising message on the display panel may be of a continuous nature,limited only by the size of the display panel desired. For example, alife-size figure of a man or woman holding the product may beimprintedon the display panel to present a particularly eye-catching andeffective sales message to the consumer.

The foregoing and other objects, features and advantages of the presentinvention will become apparent from the following detailed descriptionthereof, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a front view of the display structure illustrating the mannerin which it is segmented for folding;

FIG. 2 is a rear view of the display structure showing the support framein flattened out position;

FIG. 3 is a perspective view of the fully erected dis play structuretaken from the rear to illustrate the manner in which the supportstructure is erected; and

FIG. 4 is a perspective view of the structure from the frontillustrating the manner in which it folds and unfolds.

Turning now to the drawings, the preferred embodiment of the inventionillustrated comprises'a front dis play panel 10 and a rear supportvframe structure 12, each of which is divided transversely into aplurality of sections. Although for illustrative purposes, four sectionsare provided, it will be understood that the same principles will beapplicable to a display of fewer or more sections. Regardless of thenumber of sections, it will be understood that when completelycollapsed, the several sections will be folded upon one another to forma compact package when not in actual use (see FIG. 4).

The support frame structure is shown most clearly in FIGS. 2 and 3, withthe frame flattened out in FIG. 2 and in erected position in FIG. 3. Thesupport frame 12 preferably is formed from a single sheet of paperboardor similar self-supporting sheet material and includes an elongated backpanel 14 and a pair of side panels 16. The latter are foldably joined tothe back panel 14 by providing creases 17 which function as hinges. Thelower ends of the side panels have extensions 18 which serve as feet toaid in maintaining the structure in an upright position.

Transverse scores or fold lines 19 divide the support frame 14 into aplurality of sections. These scores may simply be creases or crimps inthe material which allow the respective sections to be folded relativeto one another.

The U-shaped configuration of the support frame in its erected position,as seen in FIG. 3, is maintained by a combination of flaps 20 andelastic tensioning bands 26. As shown in FIG. 2, each of the flaps 20 isformed by a U-shaped cut-out 21 made in the blank from which the supportframe is formed. The outer dimensions of the cut-out are larger in bothlength and width than the flap itself and the flap is integrally hingedto its respective side panel. With the front panel glued or otherwisesecured to the reverse side of the back panel 14, as shown in FIG. 3,the edge of the cut-out in the back panel, at the bottom 22 of the Uwhere it is overlayed by the front panel, provides a detent whichengages the end of the flap when its respective side panel 16 is foldedalong score 17.

Preferably, a pair of flap-detent elements are provided for each sectionof the structure to provide a sturdy, rigid construction. However,depending upon the size and configuration of the display panel, fewer ormore such flap-detent pairs may be employed.

One or more elastic bands 26 interconnect the side panel and tend tourge the side panels towards one another. This tendency is limited bythe engagement of the flaps with the respective detents, the flapsthereby acting as struts preventing the side panel from folding inwardtowards the back panel 14. By appropriate dimensioning of the length ofthe flap and the location of the detent, the side panels may bemaintained approximately 90 to the back panel in the erected positron.

The ends of the elastic bands 26, which may be of rubber or otherstretchable material, are retained in the side panels by anchor pins 27which are passed through small holes in the side panels with the bandsunder tension, and thereafter seated against the outer surfaces of theside panels to prevent withdrawal. This means for anchoring the elasticbands requires only small holes in the side panel, thereby avoiding anyweakening of the side panel and providing solid terminations for theelastic bands.

As seen best in FIG. 2, the elastic bands are positioned so that in theflattened out condition of the support frame, they overlay the flaps 20.Thus positioned, the bands insure that the flaps are retained within thecut-out from which they are formed when the structure is in itscollapsed position, as in FIG. 2. This in turn insures that the flapswill be in detent-engaging position when the sign is erected. That is,the bands prevent the flaps from being folded back up against the sidepanels to which they are hinged when the structure is collapsed.

As indicated above, the support frame 12 is separated into sections bymeans of the score or crimp lines 19 which allow it to be folded up uponitself when in the flattened-out position of FIG. 2. The display panel10 is similarly adapted to be folded along lines 11 which correspond inposition to the score lines of the support frame so that the assembledstructure may be folded. However, as illustrated in the drawings, thefold lines 11 in the display panel differ from the score lines 19 in thesupport frame.

As will be appreciated, when the sections of the structure are foldedback upon one another, as illustrated in FIG. 4, provision must be madein the display panel to accommodate the added thickness of the supportframe material behind it. Heretofore this problem has been solved bydividing the support panel into separate segments, with the spacebetween adjacent segments bridging the fold line. This in effect,avoided the problem by leaving only a single thickness of material atthe fold, but produced a less effective display.

In accordance with the present invention, the problem of accommodatingthe double thickness of material while allowing a continuous displaypanel, is solved by simply slitting or cutting through a portion of thefold line in the front panel of an extent sufficient to encompass thewidth of the support frame behind it, without removing any portion ofthe panel. Thus, as seen in the drawings, each fold line 11 in thedisplay panel includes a central portion 11a completely cut through andtwo end portions 11b which are merely crimped, in the manner of thesupport frame score lines 19, to permit folding. Further, a smalltransverse cut 11c is made at each end of the cut-through portion of thefold line to relieve the tearing forces on the panel and allow thesections thereof to expand somewhat when folded. This is illustratedclearly in FIG. 4 and as seen therein, allows the sections of thestructure to be folded back upon one another into a package whosethickness is limited essentially by the thickness of the material of thedisplay panel and support frame. At the same time, when in erectedposition, the cut through lines are practically unnoticeable and from adistance of a few feet may be effectively invisible, thereby greatlyenhancing the advertiser's choice of advertising material.

For added stability in the erected structure, the lower end of thedisplay panel 10 may be provided with a narrow flap l3 integrally hingedto the panel along its lower edge which, when erected, engages notches15 provided in the lower ends of the side panels 16.

To collapse the structure from its erected position as seen in FIG. 3,the side panels of the support frame are manually flattened outwardlyagainst the tension of the elastic bands in the region of the lowersection of the structure to allow the lower section to be foldedupwardly; see FIG. 4. The folding of the first section will provide theforce necessary to flatten out the remainder of the support frame andthereafter the remaining sections may be readily folded up to completethe collapsing.

In erecting the structure, it is necessary only to grasp an edge of theupper section of the display panel above the support frame and hold itsufficiently above the floor to permit gravity to unfold the lowersections. When the lowermost section drops, all restraint is removedfrom the elastic bands and they immediately erect the side panels andcomplete the formation of the U.-shaped support frame. The assembledstructure may thereafter simply be lowered so that it rests on the lowerflap 13 of the display panel and the feet 18 of the support frame.

From the foregoing, it will be seen that the present invention providesa simple, sturdy, self-erecting, foldable display structure with uniquecharacteristics not found in structures heretofore known. The simplifiedformation of the support frame permits easy erection thereof into asturdy supporting means, and the novel fold lines provided in thedisplay panel permits use of a' continuous panel, thereby greatlyfacilitating the task of the advertiser and increasing the versatilityof the structure. It will be understood that many modifica tions of thestructure of the preferred embodiment will occur to those skilled in theart and it is-to be understood that the invention is to be limited onlyby the scope of the following claims.

1. A foldable structure comprising a support frame having an elongatedback panel and a pair of side panels each foldably related to said backpanel along respective longitudinal edges of said back panel, wherebysaid side panels may be selectively positioned in the same plane as saidback panel or at angles with respect thereto, at least one score linetraversing the said support frame to divide it into a plurality ofsections and enable said frame to be folded when said back and sidepanels lie in the same plane, a pair of flaps respectively hinged tosaid side panels in at least one section of said frame, said flapsadapted to extend inwardly towards said back panel when said side panelsare at an angle to said back panel and to lie substantially coplanarwith said side and back panels when said panels are in the same plane, apair of cutouts formed in said back panel, each aligned with arespective one of said flaps and extending in the same direction andbeyond the ends of said flaps when said side panels are in the sameplane as said back panel, the ends of said slots forming detent means insaid back panel adapted to engage said flaps, elastic meansinterconnecting said side panels and tending simultaneously to draw saidside panels into angular relationship to said back panels and said flapsinto engagement with their respective detents, thereby to firmly retainsaid structure in said angular relationship and prevent folding of saidsupport frame, and flat front panel means secured to said back panel andadapted to collapse along with said support frame when the latter isfolded along said score lines.

2. The structure of claim 1 wherein a pair of flaps and associateddetent means are provided for each section of said support frame andwherein there is further provided separate elastic means for each ofsaid sections.

I 3. The structure of claim 1 wherein corresponding ends of both of saidside panels are enlarged to provide supporting feet for said structurewhen erected.

d. The structure of claim 3 further comprising a narrow flap extendingtransversely of said front panel means along the lower edge thereof, andnotches formed in said supporting feet for snugly receiving said flap.

5. The structure of claim 1 wherein said back and side panels and saidflaps are integrally formed from a single piece of sheet material.

6. The structure of claim 1 wherein said front panel means is continuousand substantially greater in both longitudinal and transverse dimensionsthan said support frame when folded flat, said front panel means beingadapted to be folded along lines corresponding to the score lines insaid support frame, whereby said support frame and said front panelmeans may be folded together.

7. The structure of claim 6 wherein each of the fold lines in said frontpanel means includes a cut-through portion substantially coextensivewith the transverse dimension of said support frame when flattened out,the remaining portions being scored, and wherein there is furtherprovided a relatively short cut through the panel means perpendicular tosaid fold line at each end of said cut-through portion.

8. The structure of claim 7 wherein both said support in the same planeas said back panels orat angles with respect thereto, a pair of flaps,each hinged to a respective one of said side panels, said flaps adaptedto extend inwardly towards said back panel when said side panels are atan angle to said back panel and to lie substantially coplanar with saidside and back panels when said panels are in thesame plane, a pair ofcutouts formed in said back panel each aligned with a respective one ofsaid flaps and extending in the same direction and beyond the ends ofsaid flaps when said side panels are in the same plane as said backpanel, the ends of said slots forming detent means in said back paneladapted to engage said flaps and elastic means interconnecting said sidepanels and tending simultaneously to draw said side panels into angularrelationship to said back panel and said flaps into engagement withtheir respective detents, thereby to firmly retain said structure insaid angular relationship.

10. A foldable structure comprising a support frame having an elongatedback panel and a pair of side panels each foldably related to said backpanel along respective longitudinal edges of said back panel, wherebysaid side panels may be selectively positioned in the same plane as saidback panel or at angles with respect thereto, at least one score linetraversing the said support frame to divide it into a plurality ofsections and enable said frame to be folded when said back and sidepanels lie in the same plane, a pair of flaps respectively hinged tosaid side panels in at least one section of said frame, said flapsadapted to extend inwardly towards said back panel when said side panelsare at an angle to said back panel and to lie substantially coplanarwith said side and back panels when said panels are in the same plane,detent means in said back panel adapted to engage said flaps, elasticmeans interconnecting said side panels and tending simultaneously todraw said side panels into angular relationship to said back panels andsaid flaps into engagement with their respective detents, thereby tofirmly retain said structure in said angular relationship and preventfolding of said support frame, and fiat front panel means secured tosaid back panel and adapted to collapse along with said support framewhen the latter is folded along said score lines, said back and sidepanels and said flaps being integrally formed from a single piece ofsheet material and each of said flaps being formed by providing a cutoutin said support frame prior to formation of the fold between therespective side and back panels, said cutout defining a flap integrallyconnected to said side panels along a line parallel to the subsequentlyformed fold line between said side and back panels and an opening insaid back and side panels having a length and width greater than thecorresponding dimensions of said flap. I

11. The structure of claim 10 wherein each of said detents is providedby an edge of said opening in said back panel;

12. In a foldable support frame for a display panel or the like, a backpanel and a side panel, said side panel I being foldably-related to saidback panel along a longitudinal edge thereof, whereby said side panelmay be selectively positioned in the same plane as said back panel or atan angle with respect thereto, a flap hinged to said side panel, saidflap adapted to extend inwardly towards said back panel when said sidepanel is at an angle to said back panel and to lie substantiallycoplanar with said side and back panels when said panels are in the sameplane, a cutout formed in said back panel aligned with said flap andextending in the same direction and beyond the end of said fiap whensaid side panel is in the same plane as said back panel, the end of saidslot forming detent means in said back panel adapted to engage saidflap, and elastic means connected to said side panel and tendingsimultaneously to draw said side panel into angular relationship to saidback panel and said flap into engagement with said detent, thereby tofirmly retain said structure in said angular relationship, said back andside panels and said flap being integrally formed from a single piece ofsheet material.

13, The structure of claim 12 wherein said cutout extends into said sidepanel to define said flap, said cutout having a length and width greaterthan the corresponding dimensions of said flap, said flap beingintegrally connected to said side panel along a line parallel to thefold line between said back and side panels.

1. A foldable structure comprising a support frame having an elongatedback panel and a pair of side panels each foldably related to said backpanel along respective longitudinal edges of said back panel, wherebysaid side panels may be selectively positioned in the same plane as saidback panel or at angles with respect thereto, at least one score linetraversing the said support frame to divide it into a plurality ofsections and enable said frame to be folded when said back and sidepanels lie in the same plane, a pair of flaps respectively hinged tosaid side panels in at least one section of said frame, said flapsadapted to extend inwardly towards said back panel when said side panelsare at an angle to said back panel and to lie substantially coplanarwith said side and back panels when said panels are in the same plane, apair of cutouts formed in said back panel, each aligned with arespective one of said flaps and extending in the same direction andbeyond the ends of said flaps when said side panels are in the sameplane as said back panel, the ends of said slots forming detent means insaid back panel adapted to engage said flaps, elastic meansinterconnecting said side panels and tending simultaneously to draw saidside panels into angular relationship to said back panels and said flapsinto engagement with their respective detents, thereby to firmly retainsaid structure in said angular relationship and prevent folding of saidsupport frame, and flat front panel means secured to said back panel andadapted to collapse along with said support frame when the latter isfolded along said score lines.
 2. The structure of claim 1 wherein apair of flaps and associated detent means are provided for each sectionof said support frame and wherein there is further provided separateelastic means for each of said sections.
 3. The structure of claim 1wherein corresponding ends of both of said side panels are enlarged toprovide supporting feet for said structure when erected.
 4. Thestructure of claim 3 further comprising a narrow flap extendingtransversely of said front panel means along the lower edge thereof, andnotches formed in said supporting feet for snugly receiving said flap.5. The structure of claim 1 wherein said back and side panels and saidflaps are integrally formed from a single piece of sheet material. 6.The structure of claim 1 wherein said front panel means is continuousand substantially greater in both longitudinal and transverse dimensionsthan said support frame when folded flat, said front panel means beingadapted to be folded along lines corresponding to the score lines insaid support frame, whereby said support frame and said front panelmeans may be folded together.
 7. The structure of claim 6 wherein eachof the fold lines in said front panel means includes a cut-throughportion substantially coextensive with the transverse dimension of saidsupport frame when flattened out, the remaining portions being scored,and wherein there is further provided a relatively short cut through thepanel means perpendicular to said fold line at each end of saidcut-through portion.
 8. The structure of claim 7 wherein both saidsupport frame and said front panel means are formed from self-supportingsheet material.
 9. A foldable support frame for a display panel or thelike comprising, an elongated back panel and a pair of side panels eachfoldably related to said back panel aloNg respective longitudinal edgesof said back panel, whereby said side panels may be selectivelypositioned in the same plane as said back panels or at angles withrespect thereto, a pair of flaps, each hinged to a respective one ofsaid side panels, said flaps adapted to extend inwardly towards saidback panel when said side panels are at an angle to said back panel andto lie substantially coplanar with said side and back panels when saidpanels are in the same plane, a pair of cutouts formed in said backpanel each aligned with a respective one of said flaps and extending inthe same direction and beyond the ends of said flaps when said sidepanels are in the same plane as said back panel, the ends of said slotsforming detent means in said back panel adapted to engage said flaps andelastic means interconnecting said side panels and tendingsimultaneously to draw said side panels into angular relationship tosaid back panel and said flaps into engagement with their respectivedetents, thereby to firmly retain said structure in said angularrelationship.
 10. A foldable structure comprising a support frame havingan elongated back panel and a pair of side panels each foldably relatedto said back panel along respective longitudinal edges of said backpanel, whereby said side panels may be selectively positioned in thesame plane as said back panel or at angles with respect thereto, atleast one score line traversing the said support frame to divide it intoa plurality of sections and enable said frame to be folded when saidback and side panels lie in the same plane, a pair of flaps respectivelyhinged to said side panels in at least one section of said frame, saidflaps adapted to extend inwardly towards said back panel when said sidepanels are at an angle to said back panel and to lie substantiallycoplanar with said side and back panels when said panels are in the sameplane, detent means in said back panel adapted to engage said flaps,elastic means interconnecting said side panels and tendingsimultaneously to draw said side panels into angular relationship tosaid back panels and said flaps into engagement with their respectivedetents, thereby to firmly retain said structure in said angularrelationship and prevent folding of said support frame, and flat frontpanel means secured to said back panel and adapted to collapse alongwith said support frame when the latter is folded along said scorelines, said back and side panels and said flaps being integrally formedfrom a single piece of sheet material and each of said flaps beingformed by providing a cutout in said support frame prior to formation ofthe fold between the respective side and back panels, said cutoutdefining a flap integrally connected to said side panels along a lineparallel to the subsequently formed fold line between said side and backpanels and an opening in said back and side panels having a length andwidth greater than the corresponding dimensions of said flap.
 11. Thestructure of claim 10 wherein each of said detents is provided by anedge of said opening in said back panel.
 12. In a foldable support framefor a display panel or the like, a back panel and a side panel, saidside panel being foldably related to said back panel along alongitudinal edge thereof, whereby said side panel may be selectivelypositioned in the same plane as said back panel or at an angle withrespect thereto, a flap hinged to said side panel, said flap adapted toextend inwardly towards said back panel when said side panel is at anangle to said back panel and to lie substantially coplanar with saidside and back panels when said panels are in the same plane, a cutoutformed in said back panel aligned with said flap and extending in thesame direction and beyond the end of said flap when said side panel isin the same plane as said back panel, the end of said slot formingdetent means in said back panel adapted to engage said flap, and elasticmeans connected to said side panel and tending simultaneousLy to drawsaid side panel into angular relationship to said back panel and saidflap into engagement with said detent, thereby to firmly retain saidstructure in said angular relationship, said back and side panels andsaid flap being integrally formed from a single piece of sheet material.13. The structure of claim 12 wherein said cutout extends into said sidepanel to define said flap, said cutout having a length and width greaterthan the corresponding dimensions of said flap, said flap beingintegrally connected to said side panel along a line parallel to thefold line between said back and side panels.